Answer by
amswplusone (652)

Converting Centigrade to Fahrenheit is done by multiplying by 9/5, then adding 32 to that result. So to undo that and go from Fahrenheit to Centigrade, subtract 32 from the Fahrenheit temperature, then multiply that result by 5/9. Just remember that Fahrenheit to Centigrade yields a smaller number (for temperatures above -40 degrees)) so use 5/9 to shrink the temperature.